News / Events

Report: Ultrasound Inspections on Press Washers

SDT was tasked with measuring the press washers at a major paper processing plant in Europe.

​

​First Press Wash​

dBuV(RMS)​

dBuV(Crest Value)​

Second Press Wash​

dBuV(RMS)​

dBuV(Crest Value)​

Opposite Side Hydraulic Motor​

bearing 1​

-2.4​

23​

Bearing 1​

-7​

16.8​

​

bearing 2​

4​

31.3​

Bearing 2​

-6.8​

18.5​

Engine Side Hydraulic Motor​

bearing 3​

18.1​

42.6​

Bearing 3​

17.7​

43.1​

​

bearing 4​

18.9​

42.6​

Bearing 4​

3.6​

31.2​

Ultrasound measurements were taken on 2 press washers, the first rotated at 6 rpm and the second rotated at 7 rpm.

The first press washer had a recorded value if -6.8dBuV, while the second press washer's recorded value was 4 dBuV. The difference between the two press washers is 10.8 dBuV, which show signs of early bearing degradation in the second press washer. It is important to keep a close eye on this bearing and plan for its inevitable replacement.

The time wav forms of the two wash presses are shown below.

​First Press Washer - Measurement -6.8dBuV - Y axis rescaled

Second Press Washer - Measurement 4.dBuV

The difference in signals can be viewed on the time wave spectrum. On the 7 rpm press washer you can see a solid blue area which is the ultrasonic signature of the rolling and the blue lines are the impacts of the hydraulic motor.

The spectrum for the 6 revs/min press represents a bearing that is degrading.

First Press Washer - Y axis Original Scaling

Second Press Washer - Bearing Degradation

This events showed anomalies on the rolling bearings of the two press washers. The washer that rotated at 6 revs/min had a measurement of 10.8 dBuV higher than the other washer indicating degredation. It is important to monitor this bearing closely.